I haven't seen anything about this online so I don't want to claim I am the first to figure this out. I found today that if you have the hard light shield on you can instantly switch weapons. This is even faster than having dexterity on since its an instant switch. The split second after you hit Y to switch weapons toggle your light shield on and off quickly. When you release the light shield your secondary weapon will be out thus skipping the time and animation it takes to switch and the need for dexterity which is slower than this trick anyways. I find this kinda cool if you are set up with fire power, light shield, ammo, suppresser, storm rifle, frag grenade. The suppresser for fast kills and but with how quickly it goes through ammo I have the storm rifle to instantly switch to with the light shield trick so I can quickly finish the enemy off if the suppresser runs out of ammo mid gun fight.